We demonstrate a 968-nm LD side-pumped Er:YAP laser with concave end-faces and a working frequency of 50∼1000 Hz. The maximum average powers of 26.75 and 13.18 W are obtained at 250 and 1000 Hz, corresponding to the slope efficiency of 16.2% and 9.0%, respectively. The M2 factors of 7.98 and 1.49 are determined under the multi-mode and single-mode, and three laser wavelengths of 2713, 2732 and 2796 nm are observed. The results indicate that the LD side-pumped Er:YAP crystal with negative curvature end-faces is a promising candidate for the high power and high frequency mid-infrared laser device.